aksr

A Rust derive macro that automatically generates Builder Lite pattern methods for structs, supporting both named and tuple structs with extensive customization options.

Builder Lite Pattern

aksr implements the Builder Lite pattern, where the struct itself acts as the builder. Unlike traditional builders that require a separate builder object, Builder Lite is an incremental, zero-cost evolution from the new() or Default::default() method.

Requirements:

• Struct must implement Default trait, OR
• Struct must have a new() method

This allows you to use the builder pattern without creating a separate builder type, making it especially useful for rapidly evolving application code.

Features

• 🚀 Builder Lite pattern - Zero-cost, incremental builder evolution
• 🎯 Field aliases for more intuitive API
• 📦 Vector extension methods for incremental updates
• 🔧 Flexible customization via attributes
• 💡 String optimization with &str → String and &[String] support
• 🎁 Smart Option handling for Vec<T> with empty check
• ⚡ Zero-cost abstractions following Rust best practices

Installation

Add aksr to your Cargo.toml:

[dependencies]
aksr = "0.0.5"

Examples

Run the examples to see all features in action:

cargo run --example rect        # Named struct
cargo run --example color       # Tuple struct

To see the generated code:

cargo install cargo-expand      # Install expand tool
cargo expand --example rect     # View generated code

• examples/rect.rs - Named struct with all features
• examples/color.rs - Tuple struct with all features

Supported Attributes

Attribute	Description	Values	Example
skip	Skip both getter and setter	true, false	#[args(skip = false)]
alias	Field alias for setter/getter	String	#[args(alias = "field_name")]
setter	Control setter generation	true, false	#[args(setter = true)]
getter	Control getter generation	true, false	#[args(getter = true)]
allow	Whitelist specific features	setter, getter, extend, skip	#[args(allow(xxx, xxx))]
except	Blacklist specific features	setter, getter, extend, skip	#[args(except(xxx, xxx))]
visibility	Control both getter/setter visibility	"pub", "private", "pub(crate)", "pub(self)", "pub(super)", "pub(in path)"	#[args(visibility = "pub(crate)")]
setter_visibility	Control setter visibility (overrides visibility if present)	same as above	#[args(setter_visibility = "pub")]
getter_visibility	Control getter visibility (overrides visibility if present)	same as above	#[args(getter_visibility = "pub")]
setter_prefix	Custom setter prefix	String	#[args(setter_prefix = "with")]
getter_prefix	Custom getter prefix (named / tuple)	String	#[args(getter_prefix = "field_name")] / #[args(getter_prefix = "nth")]
inline	Control inline for both getter/setter	true, false, "always"	#[args(inline = true)]
getter_inline	Control getter inline attribute	true, false, "always"	#[args(getter_inline = "always")]
setter_inline	Control setter inline attribute	true, false, "always"	#[args(setter_inline = true)]
extend	Enable extend methods for Vec	true, false	#[args(extend = false)]

License

This project is licensed under LICENSE.